are alien creatures described in Lovecraft's Dream Cycle - they are described as toad-like beings lacking eyes and sporting a mass of short tentacles on the end of their blunt snouts.
They inhabited the dark side of the Dreamlands' moon (situated in another dimension) - unlike the real-world moon the Dreamland moon had great forests and oily seas by which to support life.
Moon-Beasts were traders by nature and would give rubies in exchange for gold or slaves - employin the Men of Leng (disguised in turbans) as their go-betweeners.
The reason behind this is simple, the Moon-Beasts can not trade directly with the merchants as no one in their sane mind would work with these alien beings, who although traders are still dangerous Lovecraftian monsters that engage in many horrendous deeds - which they keep hidden from the sight of men.